1. Field
The present disclosure relates to fuel cells, and more particularly, to non-platinum (Pt) based electrode catalysts for fuel cells, methods of manufacturing the same, and fuel cells using the non-Pt based electrode catalysts.
2. Description of the Related Art
Fuel cells are electricity-generating cells that directly convert energy from chemical reactions between hydrogen and oxygen into electrical energy and may continuously generate electricity as long as hydrogen and oxygen is supplied, unlike general batteries. Unlike a general electricity generation method in which efficiency is lost during various processes, fuel cells may directly generate electricity and thus its efficiency is about two times higher than internal-combustion engine. Also, problems such as environmental pollution and resource depletion may be reduced.
Fuel cells may be classified into polymer electrolyte membrane fuel cells (PEMFCs), direct methanol fuel cells (DMFCs), phosphoric acid fuel cells (PAFCs), molten carbonate fuel cells (MCFCs), and solid oxide fuel cells (SOFCs), according to the types of electrolyte and fuel used in the fuel cells.
In general, PEMFCs and DMFCs include a membrane-electrode assembly (MEA) consisting of an anode, a cathode, and a polymer electrolyte membrane interposed between the anode and the cathode. An oxidation reaction involving fuel occurs in the anode, to which hydrogen or fuel is applied, hydrogen ions generated in the anode are transmitted to the cathode through the polymer electrolyte membrane, and a reduction reaction involving oxygen is generated in the cathode, to which oxygen is supplied, and thus a voltage difference occurs between the anode and the cathode, thereby generating electricity.
A catalyst that facilitates a reaction for generating hydrogen ions by oxidizing fuel is used in the anode of fuel cells and a catalyst that facilitates reduction of oxygen is used in the cathode.
In general, a catalyst using platinum (Pt) as an active component is used in the anode and the cathode. However, there are only small reserves of Pt-based catalysts and Pt-based catalysts are expensive. Thus, the cost of using a Pt-based catalyst makes up a large portion of the entire cost of manufacturing fuel cells and thus mass production and commercialization thereof are difficult. Therefore, development of a non-Pt based catalyst and studies for developing fuel cells having excellent performance by applying the non-Pt based catalyst are being performed.